... 3.CNC Tool holders high precision:0.005mm,0.008mm er collet ,material :65Mn hardness:HRC44-48 ER COLLET TYPE:2,3,4 ... ,8,9,10,11,12,13,14,1high precision:0.005mm,0.008mm er collet ,material :65Mn hardness:HRC44-48ER COLLET TYPE ... of special elastic steel material:65Mn. hardness:HRC44-48 high precision:8u(0.008mm),5u(0.005mm) all kind of er colle ER Collets